The "cities" are to enter negotiations with the Government to take on powers and responsibilities that will give them greater scope to thrive.

The so-called City Deals - the first eight of which were announced last year - will give participating areas the ability to use budgets better for local needs such as training and skills, roads and other developments.

In return, the areas must demonstrate they have a strong plan for local growth. The Government said it would work closely with cities to negotiate a deal over the next year.

Speaking at Mansion House in the City, Mr Clegg said: "Even more places will be free from Whitehall control and have the tools to power their own growth. These deals help cities and their wider areas make once in a generation changes that will be felt by everyone across their region.

"Letting go of power and money doesn't come naturally to Whitehall. Over time, the economic importance of other parts of the country has been devastatingly downplayed, as the economic elite have narrowed the debate towards a London-centric view.

"Rather than let our industries and communities wither, we need to free up cities outside of London that have their own unique selling points."

The 20 areas announced are: the Black Country; Bournemouth and Poole; Brighton and Hove; Greater Cambridge; Coventry and Warwickshire; Hull and Humber; Ipswich; Leicester and Leicestershire; Milton Keynes and the South East Midlands; Greater Norwich, Oxford and Oxfordshire; Reading and Central Berkshire; Plymouth; Preston; Southampton and Portsmouth; Southend and Thames Gateway South Essex; Stoke and Staffordshire; Sunderland and the North East; Swindon and Wiltshire; and Tees Valley.

Together with the first eight cities that concluded deals last July, the areas account for 71% of the population of England and 68% of the jobs.

Financial Secretary to the Treasury and Minister for Cities, Greg Clark, said: "Each city is unique, yet for decades Whitehall has treated them as being the same - there has been too little sense of place in government policy."